1. Field of the Invention
The present invention relates generally to apparatus and process for laser-assisted drilling, and more particularly to laser-assisted drilling which utilizes laser energy to alter the molecular structure of an object and then utilizes mechanical action to abrade the altered structure to remove it from a given site. While the present invention has particular application to a laser assembly suited for dental applications, the teachings of this invention may be applicable to other drilling systems.
2. Description of the Prior Art
Laser assemblies are known to be used in dental procedures such as the eradication of carious lesions (removal of dental decay), treatment of sensitive teeth, removal off soft tissue, enamel, etc., and for restorative work, etc. In all known dental applications, laser energy is used directly and unassisted, either by focused beam or through an optical point, for removing the unwanted material and/or altering the tooth structure. U.S. Pat. No. 4,818,230 to Myers, et al., discloses such a system in which pulsed laser energy is aimed at the tooth decay and repeatedly applied until the decay is eradicated from the tooth. The laser is a yttrium-Aluminum-Garnet (YAG) laser having a pulsewidth of 50-2000 microns, a pulse duration of a picosecond to several milliseconds, and an energy of 0.1-100 millijoules.
U.S. Pat. No. 4,940,411 to Vassiliadis, et al., is another known dental laser system in which a Neodymium doped yttrium-Aluminum-Garnet (Nd:YAG) laser is used to eliminate; the unwanted material, and a helium-neon (HeNe) laser is used as a pointing device to illuminate the area to be removed by the more powerful Nd:YAG laser. The Nd:YAG laser has a pulse repetition rate of between 1 and 10,000 pulses per second, an average power of up to 50 watts, a pulse duration of between 1 picosecond and several milliseconds, and a peak energy of up to 5 joules per pulse.
One difficulty with all such known dental laser devices is that the dentist has no tactile sensation for controlling the drilling process. That is, the dentist does not have the "feel" for how much and what type of material is being eliminated from the tooth. With known mechanical dental drills, the dentist can apply the correct amount of pressure to the correct location, and can also feel what effect the drill is having on the tooth. Thus, with a mechanical dental drill, the dentist's hand becomes a very effective force applicator and an extremely fine sensor. Without this contact with the tooth, as with known laser dental systems, the dentist can no longer accurately apply energy to the tooth or sense the tooth structure, itself, by "feel".
Another problem with known dental laser systems applied to hard tissues is safety. Application of laser energy sufficient to remove hard tooth structure by ablation may cause some damage in soft tissues if the laser accidentally strays or is reflected from an instrument such as a dental mirror.
Yet a further problem with known dental laser systems is long-term patient comfort. Known high-power dental lasers may cause gross thermal damage to the tooth, damaging the dental nerve. This is especially true since it is quite difficult to control the depth of laser-induced change with a known laser device working on tooth structure.
Yet another problem with known dental laser systems is their high cost. Most dentists already possess a mechanical dental drill, and to purchase and install a laser system which does not also safely reduce hard dental tissues will require a great deal of additional space, time, and expense.
While the above-noted drawbacks of dental laser systems have thus far prevented their universal acceptance in hard-tissue dentistry, the well-known problems of noise, vibration, and pain associated with mechanical dental drills have produced a pronounced aversion to dental visits among many patients. Therefore, what is needed is an entirely new dental drilling modality which combines the advantages of both the laser and mechanical drilling systems.